ANALYSIS OF AIR-BUBBLE PLUMES

Abstract

Models are developed to describe the gross behavior of air-bubble plumes generated by point and line sources of air-bubbles released in stagnant water bodies of uniform density. The models predict plume width, velocities, and induced flow rates as a function of elevation above the source. The analysis is confined to the plume mechanics and does not include the horizontal flow created at the surface by the plume. An integral similarity approach, similar to that used for single-phase buoyant plumes, is employed. Governing equations are found by applying conservation of mass, momentum, and buoyancy. The compressibility of the air and the differential velocity between the rising air bubbles and water are introduced in the buoyancy flux equation. Generalized solutions to the normalized governing equations are presented for both point and line sources of air-bubbles. The results of the analyses are compared with existing large-scale experimental data. The comparisons indicate that the models predict the gross behavior of plumes well and yield estimates of the entrainment coefficients and lateral spreading ratios.